When it comes down to it, civilization is all about energy usage. From wood fire, to coal, to atomic energy you can follow the progress of humanity in terms of how much energy we are capable of harnessing. On the Kardashev scale, a Type I civilization would be capable of using all of the energy on its planet, a Type II civilization could use all the energy from its local star, and a Type III civilization could harness all the energy in a galaxy. Carl Sagan thought humans currently sit around 70% of a Type I civilization. That milestone will be fully reached at some point in the next few hundred years and then humanity might move on to the construction of a Dyson sphere (or a Dyson swarm) around the Sun.
Kurzgesagt explains what a Dyson Swarm is and explores what would go into building one in the video above. I love that harvesting most of the Sun’s energy would require harvesting some of the suns energy. Nice feedback loop. Oh, and we would have to completely dismantle the planet Mercury in order to have enough raw materials to build the thing.